1. Field of the Invention
The present invention relates to a fuel supply apparatus for an internal combustion engine and, more particularly, to a fuel supply apparatus for an internal combustion engine comprising a reservoir arranged within a fuel tank of the motor vehicle, from which fuel is drawn into a fuel feed unit and fed to an internal combustion engine, a return line, by which fuel supplied by the fuel feed unit and not burned by the internal combustion engine is fed back to the fuel tank and a jet pump connected with the return line by which fuel is fed from the fuel tank into the reservoir.
2. Prior Art
This type of fuel supply apparatus is described by DE 195 04 565 A1. This fuel supply apparatus has a reservoir arranged in a fuel tank of the motor vehicle, from which fuel is drawn into a fuel feed unit and fed to the internal combustion engine of the motor vehicle. Furthermore a return or feedback line is provided, through which unburned fuel is fed back into the fuel tank from the internal combustion engine. A jet pump is connected to the return line, through which fuel is supplied to the reservoir from the fuel tank. The jet pump guarantees that a sufficient fuel supply is present in the reservoir, from which the fuel feed unit draws fuel. The jet pump is continuously operated with the quantity of fuel fed back through the return line. When the reservoir is completely filled fuel fed back through the return line overflows from it into the fuel tank. Under certain operating conditions of the internal combustion engine, for example in the idle state or with reduced load, the fuel quantity fed back through the return line is comparatively large so that a correspondingly large amount of overflow from the reservoir results. The fuel fed back through the return line is generally more or less strongly heated, so that the total fuel volume present in the fuel tank is heated by the overflowing reservoir. This makes it difficult to satisfy certain regulations for tightness of the fuel supply tank, which control the amounts of certain environmentally harmful substances, such as hydrocarbons, which may escape from the fuel tank within a certain time interval.
It is an object of the present invention to provide an improved motor vehicle supply apparatus for an internal combustion engine of a motor vehicle that does not have the above-described disadvantage.
This object, and others which will be made more apparent hereinafter, are attained in a fuel supply apparatus for an internal combustion engine of a motor vehicle, which comprises a reservoir arranged within a fuel tank of the motor vehicle, from which fuel is drawn into a fuel feed unit and fed to an internal combustion engine; a return line, by which fuel supplied by the supply unit and not burned by the internal combustion engine is fed back to the fuel tank; and a jet pump connected with the return line by which fuel is fed from the fuel tank into the reservoir.
According to the invention a control valve is arranged in the return line upstream from the jet pump, which has a floating body which floats in fuel in the reservoir when the reservoir in nearly or completed in a filled state, which moves a control element of the control valve so that in a first position of the control element when the reservoir is not nearly in a filled state a connection is made between the jet pump and the return line and in a second position when the reservoir is at least nearly in a filled state the connection between the jet pump and the return line is broken and the return line opens into the reservoir.
The fuel supply apparatus according to the invention has the advantage that the reservoir is filled by the jet pump only if it has not yet reached the nearly or completely filled state. When the nearly or completely filled state has been reached the jet pump is disconnected and the reservoir is only filled with fuel fed back directly from the return line without passing through the jet pump so that the overflow from the reservoir is reduced and the heating of the fuel in the fuel tank is reduced. This allows the regulations regarding tightness of the fuel tank to be satisfied and maintained.
Preferred embodiments provide further advantages and features.
In a preferred embodiment of the invention the control valve is integrated or mounted in a simple manner in the reservoir or in a cover closing the reservoir. In another preferred embodiment the control element of the control valve is pressure compensated so that no or very little force acts on it in its motion direction by the pressure in the return line. Then only little force is required to move it. In an especially preferred embodiment the control element of the control valve is moved by the force of gravity into its first position. In another embodiment a pressure limiting valve is integrated into the control valve which is arranged upstream relative to the return flow.